Spin dyeing of polyacrylonitrile fibers with 1-30 parts per million of polymethine and triarylmethane dyes



United States Patent 3,254,046 SPIN DYEING OF POLYACRYLONITRILE FIBERS WITH .-130 PARTS PER MILLION 0F POLY- METHINE AND TRIARYLMETHANE DYES Corrado Mazzolini and Carlo Gabutti, Mestre, Venice, Italy, assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed June 24, 1963, Ser. No. 209,161 8 Claims. (Cl. 26032.6)

The present invention relates to acrylic fibers which are obtained from acrylonitrile polymers and copolymers and which have superior whiteness. It is known that the color of the acrylic fibers from acrylonitrile polymers and copolymers with other vinyl monomers tends somewhat toward yellow, so that it is necessary to correct the original color of the fiber by the addition of the spinning solution of small amounts of pigments having a color complementary to the yellow of the fibers so as to shift the color of the latter toward white. There are customarily used pigments of good fastness to light and heat, and which are also stable to bleaching treatments with hypochlorite, used for cotton, and with hydrogen peroxide, used for W001, so that the corrected fiber can be used mixed with cotton and with wool without danger that with the bleaching of the cotton or of the wool, the color of the carylic fiber will be impaired.

The use of these-pigments, however, in addition to in-.

VOlving practical difiiculties such as the necessity of an accurate dispersion, since insoluble, in the spinning solution and substantial decrease in luster of the fiber, so that it cannot be used when it is desired to obtain a bright fiber, has the serious drawback of making impossible chlorite bleaching which is the most effective method and which is necessary in the industry when it is desired to obtain the maximum whiteness of the acrylic fibers. As a matter of fact, chlorite bleaching does away with the yellow of the fiber, but leaves the pigments unchanged which thus impart to the fiber a bluish shade which is not acceptable. Hence the necessity of producing two types of fibers, a type having a very low content of pigments intended for industrial chlorite bleaching, and a type having a higher content of pigments, which is not to be subjected to industrial bleaching.

The object of the present invention is now to obtain acrylic fibers having whiteness characteristics which remain unchanged even after bleaching treatments with hypochlorite and hydrogen peroxide and which are capable of further improvements by chlorite bleaching.

Another object of the present invention is to obtain acrylic fibers having an excellent original color, fastness to heat and to light, and a higher luster than that of the fibers to which pigments have been added.

Still another object of the present invention is to obtain a unique type of acrylic fiber which may be subjected either to hypochlorite bleaching or to chlorite bleaching without any impairment of the color.

It has been found that the basic dyes of red-blue-violet color, soluble in the spinning solution and stable to light and heat can be more advantageously used in quantities of from 0.1 to- 30 p.p.m. in substitution for or in addition to the pigments, in order to correct the yellow of the acrylic fibers. As a matter of fact, they are resistant to hypochlorite and hydrogen peroxide bleaching, but are not resistant to chlorite bleaching, for which reason no CROSS EFERiZiiSE undesired added coloration appears with this type of bleaching.

The acrylic fibers obtained by using the basic dyestuffs indicated above have an improved original color, excellent color fastness to light and to heat, and furthermore, the advantage that they can be used for any application, regardless of the type of bleaching to which they must be subjected during the course of the working, thus avoiding the preparation of several types of fibers.

Furthermore, the correction of the color of the fiber with basic dyestuffs can be used also in the obtaining of lustrous fibers since these dyestuffs, contrary to the pigments, do not have delustering effects.

The advantages resulting from the use of these dyestuffs will be shown better by the results of the following tests set forth in the following examples, carried out by way of comparison on untreated fibers, on pigment-containing fiber, on fiber prepared in accordance with the invention containing the basic dyestuffs, and on fiber containing basic dyestuffs in addition to pigments.

For the evaluation of the color, reference is made to the C.I.E. System of representing and measuring color. In this system, color is expressed in terms of dominant wavelength (DWL), purity (P) and brightness (B), referred to thestandard illuminant C, a source of emission corresponding to a black body at 6200 K. Whiteness (W) is derived by the formula:

in which B=brightness p*=purity multiplied by a correction factor as set out in the Journal of the Optical Society of America, vol. 28, page 52 (1938), and pulications of the National Bureau of Standards in Paper Trade Journal, vol. 103-108, page 38 (1936).

EXAMPLE NO. 1

A solution of an acrylonitrile copolymer of 94% acrylonitrile and 6% vinyl acetate in dimethyl acetamide, obtained from 40 kg. of polymer dissolved in 114 kg. of dimethylacetamide without special correctives and containing 0.2 kg. of Ti0 as delustrant was wet spun at about C. into a bath composed of 50 parts of dimethylacetarnide and 50 parts of water. The fiber obtained, after having been subjected to the customary heatstabilization treatments in steam above C. had the following color characteristics, measured with a General Electric spectrophotometer.

D WL: 575 mu W=low, non-measurable EXAMPLE NO. 2

' To a spinning solution prepared in accordance with Example 1, there was added 0.440 gram of a phthalocyanine pigment known on the market as Monastral Blue (CI. 74160) and 0.440 gram of a pigment known on the market as Platinum Violet (CI. 60010) and 200 grams of TiO delustrant which has already been dispersed in 1400 grams of dimethylacetamide. The fiber which was obtained by wet spinning, as indicated in the preceding example, had the following color characteristics:

The fiber thus obtained is subjected to the following bleaching treatments:

(a) Bleaching with hypochlorite (b) Bleaching with hydrogen peroxide 1 kg. of fiber is treated at 50 C. for 12 hours with 15 liters of water containing 2 vol. per liter of active oxygen as hydrogen peroxide, 130 volumes concentration, and 5 grams of tetrasodium pyrophosphate or ammonia, until obtaining a pH of 8.2.

The bath is removed and the fiber is treated at 40 C. for 4 hours with 15 liters of water containing 150 grams of stabilized sodium hydrosulfite. The bath is removed and the fiber is washed for minutes with liters of water containing 15 cc. of sulfuric acid of 66 B.

The fiber, after washing and centrifuging, had the following color characteristics:

DWL=560 P=1.6

B=75.3 W=84.5 (F: 1)

(c) Bleaching with chlorite 1 kg. of fiber is immersed in a bath composed of 15 liters of water containing 30 grams of 80% sodium chlorite, 30 grams of oxalic acid, 30 grams of sodium nitrate and 10 grams of a dispersing agent.

The bath which contain-s the fiber is brought to the boiling point and held at this point for 30 minutes. Thereupon the bath is cooled to 70 C., 15 grams of sodium metabisulfite are added, and the bath is then maintained at 70 C. for 10 minutes. The bath is removed and the fiber is neutralized by treatment at 60 C. for 10 minutes with 15 liters of water containing 7.5 grams of sodium carbonate. The fiber after being washed and centrifuged had the following color characteristics:

DWL=496 P=2.3

EXAMPLE NO. 3

To the spinning solution prepared in accordance with Example 1, there was directly added, without preliminary dispersion, 800 mg. of basic dyestuff of the polymethine series Astrazon Violet F3 RL (C.I. 48020) and 140 mg. of basic dyestuif of the triphenylmethane series Astrazon Blue B (Cl. 42140).

The fiber obtained by extrusion as in Example 1 had the following color characteristics DWL=571 P=1.6

The fiber thus obtained is subjected to the following bleaching treatments:

(a) Bleaching with hypochlorite The fiber is subjected to a bleaching treatment with hypochlorite as described in Example 2.

The fiber, after treatment in this manner, had the following color characteristics:

(b) Bleaching with hydrogen peroxide The fiber is subjected to a bleaching treatment with hydrogen peroxide in the manner described in Example 2.

The fiber, after treatment in this manner, had the following color characteristics:

DWL=571 P=1.7

(c) Bleaching with chlorite The fiber is subjected to a bleaching treatment with chlorite in the manner described in Example 2. The fiber after treatment in this manner had the following color characteristics:

B=86.6 W=93.5 (F: 1)

EXAMPLE NO. 4

To a spinning solution prepared in accordance with Example 1, there was added mg. of Monastral Blue pigment, 80 mg. of Platinum Violet pigment, 80 mg. of Astrazon Blue and 600 mg. of Astrazon Violet Basic dyestuff.

The fiber which was obtained by wet spinning as described in Example 1 had the following color characteristics:

DWL=566 P=1.5 13:75.3 W=86.3 (F= 1) The fiber thus obtained is subjected to the following bleaching treatments:

(a) Bleaching with hypochlorite The fiber is subjected to a bleaching treatment with hypochlorite in the manner described in Example 2. The fiber after having been treated in this manner had the following color characteristics:

(b) Bleaching with hydrogen peroxide The fiber is subjected to a bleaching treatment with hydrogen peroxide in the manner described in Example 2.

The fiber after treatment in this manner had the following color characteristics:

DWL=560 (c) Bleaching with chlorite methine series and the triphenylmethane series and mixtures thereof which are color stable to bleaching with hypochlorite and hydrogen peroxide bleach baths, but not color stable to bleaching with chlorite bleach baths.

- 3. In the process for producing acrylonitrile fibers by extruding a spinning solution of an acrylonitrile polymer of at least 80 percent acrylonitrile and up to percent of at least one other copolymerized monoolefinic monomer dissolved in a dimethylcarbamylsolvent therefor into a coagulating medium for the polymer, the improvement comprising adding to said spinning solution from 0.1 to parts per million by weight of the acrylonitrile polymer of a basic dyestuif soluble in the said solvent and selected from the group consisting of blue and violet basic dyestuffs of the polymethine series and the triphenylmethane series and mixtures thereof, which are color stable to bleaching with hypochlorite and hydrogen peroxide bleach baths, but not color stable to bleaching with chlorite bleach baths.

4. In the process for producing acrylonitrile polymer fibers by extruding a spinning solution .of an acrylonitrile polymer at least 80% acrylonitrile and up to 20% of at least one other copolymerized mono-olefinic monomer dissolved in dimethylacetamide into a coagulating bath for the polymer comprising a mixture of dimethylacetamide and water, the improvement comprising adding to TABLE I Color Color of 1 of Fiber Color of Fiber With Addition of Pigments Fiber With Color of Fiber With Addition of Without Addition of Pigments and Dyes Additives B asia Dyes (Ex. 1) (Ex. 2) (Ex. 3) (Ex. 4)

After After After Bleaching Bleaching Bleaching Hypo.

Initial Initial With With With Initial Initial chlorite H2O; Chlorite Hypo- H1O, Chlorite chlorite 1 Non-measurable.

We claim:

1. In the process for producing acrylonitrile polymer fibers by extruding a spinning solution of an acrylonitrile polymer at least 80 percent acrylonitrile and up to 20 percent of at least one other copolymerized monoolefinic monomer dissolved in dimethylacetamide into a coagulating bath for the polymer comprising a mixture of dimethylacetamide and water, the improvement comprising adding to said spinning solution from 0.1 to 30 parts per million by weight of the acrylonitrile polymer of a basic dyestuif soluble in dimethylacetamide and selected from the group consisting of blue and violet basic dyestuffs of the polymethine series and the triphenylmethane series and mixtures thereof which are color stable to bleaching with hypochlorite and hydrogen peroxide bleach baths, but not color stable to bleaching with chlorite bleach baths.

2. In the process for producing acrylonitrile fibers by extruding a spinning solution of an acrylonitrile polymer of at least 80 percent acrylonitrile and up to 20 percent of at least one other copolymerized monoolefinic monomer dissolved in dimethylacetamide and containing a small amount of at least one pigment effective to produce a whiter color in the resulting fiber into a coagulating bath for the polymer comprising a mixture of dimethylacetamide and water, the improvement comprising adding to said spinning solution from 0.1 to 30 parts per million by weight of the acrylonitrile polymer of a basic dyestuif soluble in dimethylacetamide and selected from the group consisting of blue and violet basic dyestuffs of the polysaid spinning solution from 0.1 to 30 parts per million by weight of the acrylonitrile polymer of a mixture of basic dyestuffs of Color Index 48020 and Color Index 42140.

5. In the process for producing acrylonitrile polymer fibers by extruding a spinning solution of acrylonitrile polymer at least acrylonitrile and up to 20% of at least one other copolymerized mono-olefinic monomer dissolved in dimethylacetamide and containing a small amount of at least one pigment effective to produce a whiter color in the resulting fiber into a coagulating bath for the polymer comprising a mixture of dimethylacetamide and water, the improvement comprising adding to said spinning solution from 0.1 to 30 parts per million by weight of the acrylonitrile polymer of a mixture of basic dyestuffs of Color Index 48020 and Color Index 42140.

6. In the process for producing acrylonitrile polymer fibers by extruding a spinning solution of acrylonitrile polymer at least 80% acrylonitrile and up to 20% of at least one other copolymerized mono-olefinic monomer dissolved in a dimethylcarbamyl solvent therefor into a coagulating medium for the polymer; the improvement comprising adding to said spinning solution from 0.1 to 30 parts per million by weight of the acrylonitrile polymer of a mixture of basic dyestuffs of Color Index 48020 and Color Index 42140.

7. The process of claim 4 wherein the acrylonitrile polymer is a copolymer of 94% acrylonitrile and 6% vinyl acetate.

8. The process of claim 5 wherein the acrylonitrile polymer is a copolymer of 94% acrylonitrile and 6% vinyl acetate.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 1,056,803 10/1953 France. 846,148 8/1960 Great Britain.

OTHER REFERENCES Leddy, American Dyestufl Reporter, Apr. 18, 1960, pp. 57-58, 65-68 and double page showing FIGS. 2-7, and 11-14.

S 11' mg 2 Ciba Review, 1962/4, pages 4243, re e ved 111 US, Surfer a 1 1 Patent Office ct. 16, 1942. TP 890 c5,

Color Index, vol. I, pp. 1635 and 1640, vol. 2, p.

Mefian et a1 2479, vol. 4, page 4011, 2nd ed., pub. 1956 by the Society Straley et a1 26041 of Dyers and Colourists, Yorkshire, England. Jones 855 Hoefle l5 NORMAN G. TORCHIN,PrimaIy Examiner. 

1. IN THE PROCESS FOR PRODUCING ACRYLONITRILE POLYMER FIBERS EXY EXTRUDING A SPINNING SOLUTION OF AN ACRYLONITRILE POLYMER AT LEAST 80 PERCENT ACRYLONITRILE AND UP TO 20 PERCENT OF AT LEAST ONE OTHER COPOLYMERIZED MONOOLEFINIC MONOMER DISSOLVED IN DIMETHYLACETAMIDE INTO A COAGULATING BATH FOR THE POLYMER COMPRISING A MIXTURE OF DIMETHYLACETAMIDE AND WATER, THE IMPROVEMENT COMPRISING ADDING TO SAID SPINNING SOLUTION FROM 0.1 TO 30 PARTS PER MILLION BY WEIGHT OF THE ACRYLONITRILE POLYMER OF A BASIC DYESTUFF SOLUBLE IN DIMETHYLACETAMIDE AND SELECTED FROM THE GROUP CONSISTING OF BLUE AND VIOLET BASIC DYESTUFFS OF THE POLYMETHINE SERIES AND THE TRIPHENYLMETHANE SERIES AND MIXTURES THEREOF WHICH ARE COLOR STABLE TO BLEACHING WITH HYPOCHLORITE AND HYDROGEN PEROXIDE BLEACH BATHS, BUT NOT COLOR STABLE TO BELACHING WITH CHLORITE BLEACH BATHS. 